Encyclopedia of Health and Medicine

I
immune disorders Chronic conditions of the
IMMUNE SYSTEM that affect the IMMUNE RESPONSE and
the body’s ability to protect and defend itself
against INFECTION. Immune disorders generally
result from a deficiency or absence of some component
or structure of immune function. Such a
deficiency may be primary, which is congenital
(present at birth), genetic (inherited), or acquired
(develops during life). People who have had their
spleen surgically removed (SPLENECTOMY) also have
reduced immune response, which results in
increased susceptibility to infection.
cure or end the condition. Common medication
therapies for immune disorders include ANTIHISTA-
MINE MEDICATIONS, NONSTEROIDAL ANTI-INFLAMMATORY
DRUGS (NSAIDS), CORTICOSTEROID MEDICATIONS,
leukotriene receptor antagonists, MAST CELL stabilizers,
and DISEASE-MODIFYING RHEUMATOID DRUGS
(DMARDS). The particular medication regimen
depends on the immune disorder and the individual’s
symptoms.
See also ANTIBODY; ATOPY; GENETIC DISORDERS;
IMMUNITY; IMMUNOCOMPROMISED; IMMUNODEFICIENCY;
LEUKOTRIENES; LIVING WITH IMMUNE DISORDERS.
AUTOIMMUNE DISORDERS
HIV/AIDS
HYPERSENSITIVITY REACTION
lgA NEPHROPATHY
IgE deficiency
PARTIAL COMBINED
IMMUNODEFICIENCY (PCID)
TOXIC EPIDERMAL NECROLYSIS
IMMUNE DISORDERS
COMMON VARIABLE IMMUNE
DEFICIENCY (CVID)
IMMUNOGLOBULIN A (IgA)
deficiency
IgM deficiency
SEVERE COMBINED IMMUNODEFICIENCY
(SCID)
Wegener’s granulomatosis
Frequent or chronic infection is the primary
symptom of an immune disorder other than
HYPERSENSITIVITY REACTION (allergy). BLOOD tests for
immunoglobulins and antibodies generally can
diagnose immune disorders. Hypersensitivity reactions
generate symptoms according to the type of
reaction and may include symptoms of ALLERGIC
RHINITIS, ALLERGIC CONJUNCTIVITIS, ALLERGIC DERMATI-
TIS, or ALLERGIC ASTHMA. ALLERGY TESTING is the preferred
diagnostic approach for identifying the
allergens responsible for hypersensitivity reaction,
though often a person knows the cause of an
allergy.
Immune disorders are generally chronic, which
means treatment can improve symptoms but not
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immune response The multiple mechanisms and
processes through which the body identifies and
reacts to antigens. The immune response is the
body’s primary means of protecting itself from
INFECTION. There are three independent yet complementary
immune response pathways: ANTIBODY-
MEDIATED IMMUNITY (also called humoral
immunity), CELL-MEDIATED IMMUNITY, and the COM-
PLEMENT CASCADE. As well, the immune response
stimulates activity from the NERVOUS SYSTEM and
the endocrine system.
The immune response relies largely on ANTI-
BODY–ANTIGEN binding. Antigens are molecules that
identify cells to the IMMUNE SYSTEM. Antibodies are
molecules the immune system produces to bind
with nonself antigens—antigens on cells that do
not belong to the body. With antibody–antigen
binding, the antibody releases proteins called
opsonins that mark the antigen-bearing cell for
destruction by killer T-cells and natural killer (NK)
cells. Monocytes (in the BLOOD circulation) and
macrophages (in the tissues) consume the cellular
debris remaining after the marked cell’s destruction.
Antibody–antigen binding also activates the
complement cascade, a biochemical response that